Bethesda fans can rest assured now; they weren't going crazy. Starfield is a very real game, and it's the next title to be released by Bethesda Game Studios after Fallout 76.
The developer, however, did not share far too many details about the game, except to affirm its existence, and that it's an entirely new IP from the company that is set in space. Bethesda also shared a short teaser for the upcoming title that shows a pentagonal ship presumably going into hyperspace.
At present, that's about all they shared with us, although it does represent the company's first new franchise in a quarter of a century.